1. Field of the Invention
The present invention relates to systems and methods for protecting vehicle occupants from injury. More specifically, the present invention relates to a compact tethering system for maintaining the position of a cushion of an airbag system, such as an inflatable curtain designed to protect vehicle occupants against lateral impact.
2. Description of Related Art
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the explosion of pressurized gas from an inflator. Expanding gases from the inflator fill the airbags, which immediately inflate to protect the driver and/or a passenger from impact against the windshield, dashboard, and steering wheel.
Side impact airbags have also been developed in response to the need for protection from impact against the side of the vehicle (also known as lateral impact). These airbags, which are commonly referred to as xe2x80x9cinflatable cushionsxe2x80x9d or xe2x80x9cinflatable curtains,xe2x80x9d may be mounted in the vehicle over the doors, and may inflate during an accident to cover the windows, doors, and lateral surfaces of the vehicle. The inflatable cushion may also be connected to tethers that extend from the ends of the airbag to anchoring points within the vehicle. These tethers may exert tension on the inflated cushions to keep the cushions generally between the occupant and the lateral surface of the vehicle.
However, tether systems known in the art have a number of disadvantages. First of all, many known tether systems require that the tether be extended longitudinally away from both ends of the inflatable cushion. Consequently, the front tether must be extended from the front end of the inflatable cushion toward the front of the vehicle and the rear tether must be extended from the rear end of the inflatable cushion toward the rear of the vehicle. Such a design is incompatible with most trucks and sport utility vehicles (xe2x80x9cSUVsxe2x80x9d) in which the passenger compartment of the vehicle ends abruptly behind a lateral surface over which it would be desirable to position a cushion. In these vehicles, there is typically insufficient space for tether extension rearward from the edge of the inflatable cushion. Accordingly, most known tethering systems cannot be used.
One of the main purposes in attaching a tethering system to an inflatable cushion is to protect the occupant by applying tension to the inflatable cushion to keep the inflatable cushion in the proper position. Without such tension, there is an inherent risk that the inflatable cushion will improperly inflate and injure the occupant. Additionally, during rollover conditions, if the inflatable cushion is not secured in the proper position via tethers, the motion of the occupant may force the inflatable cushion out of an open window, thereby eliminating any possible safety benefits of the inflatable cushion.
Furthermore, side impact inflatable cushions are often classified according to the compaction process used to compact the inflatable cushion. In general, there are two different categories of cushions: those that are compacted by rolling and those that are compacted by accordion folding. However, many previously known tethering systems are designed for use with a specific compaction process; as a result, they cannot be used with both rolled and accordion-folded cushions. Rather, a specific tethering system must often be designed for each type of inflatable cushion. As a result, the cost-effectiveness and interchangeability of known inflatable cushions have suffered somewhat.
Additionally, many known inflatable cushions and tethering systems provide insufficient tension to prevent occupant excursion. xe2x80x9cOccupant excursionxe2x80x9d occurs when all or part of the vehicle occupant is extended or ejected from the vehicle, usually through an open door or window, during an accident. Obviously, occupant excursion can be very dangerous, especially during rollover conditions. However, since many known tethering systems permit the airbag cushion to move far enough to expose the window and door of the vehicle, these systems may not provide sufficient protection against occupant excursion.
Similarly, xe2x80x9cbag slapxe2x80x9d may occur when the cushion inflates inward of the window or door to strike an occupant. Many known tethering systems provide inadequate protection against bag slap.
Accordingly, a need exists for a tethering system suitable for use in vehicles that do not have sufficient interior space behind the inflatable cushion to extend a rear tether. Furthermore, a need exists for such a tethering system that tensions the cushion tightly enough to keep the cushion in place during inflation and impact of an occupant against the cushion. Such a tethering system should be cost effective to manufacture and install, and should preferably be usable with cushions folded by any common method.
The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently tethering systems. Thus, it is an overall objective of the present invention to provide tethering systems and related methods that provide adequate tension to prevent occupant excursion without requiring a great deal of space in the vehicle, and without requiring the use of a specific cushion folding process.
To achieve the foregoing objective, and in accordance with the invention as embodied and broadly described herein in the preferred embodiment, an enhanced tethering system and method are provided. According to one configuration, an inflatable curtain module may incorporate a cushion attached to a front tether anchoring point within the vehicle by a front tether, and to a rear tether anchoring point by a tether attachment assembly.
In the case of a vehicle with an abrupt rear surface, such as a truck or SUV, the rear tether anchoring point may be generally perpendicular to, or at least laterally offset from, the cushion in the deployed configuration. For example, the rear tether anchoring point may be on or near an abrupt rear surface, near the junction of the vehicle roof with the abrupt rear surface. The tether attachment assembly may be used to provide longitudinal tension on the inflated cushion despite the limited longitudinal space within the passenger compartment of the vehicle.
More specifically, the tether attachment assembly may have a rear tether connected to the cushion and to the vehicle at the rear tether anchoring point. An intermediate portion of the rear tether may pass within a tether restraint assembly designed to divert the rear tether such that the tether pulls the cushion rearward instead of pulling the cushion inward, toward the rear tether anchoring point. The tether restraint assembly may have a tether restraint member attached to a vehicle surface at first and second restraint anchoring points such that the intermediate portion is captured between the tether restraint member and the vehicle surface. The tether restraint member may, for example, take the form of a flexible strap similar in structure to the tether.
When the cushion is in the stowed configuration, the rear tether may extend directly rearward of the cushion to pass within the tether restraint assembly, and may then extend generally perpendicular to the cushion to reach the rear tether anchoring point. Upon deployment of the cushion, the rear tether may be pulled downward so that the intermediate portion slides along the tether restraint assembly.
If the cushion has been accordion folded, the rear tether may be substantially untwisted during deployment. If the cushion has been rolled, the rear tether may twist to accommodate unrolling of the cushion. The tether restraint assembly accommodates such twisting. Regardless of whether twisting of the rear tether has occurred, the front and rear tethers may then cooperate to tension the cushion along the bottom edge of the cushion, thereby protecting the occupant against bag slap caused by inward inflation of the cushion, or against excursion from the vehicle.
According to one alternative embodiment, the tether restraint member may instead be a rigid member. For example, the tether restraint member may take the form of a bar attached to the vehicle surface in a manner similar to the strap. The rear tether may then respond to deployment of the cushion in a manner similar to that described above to keep the cushion in place.
Through the use of the tethering systems of the present invention, an occupant of a vehicle can be protected from both inward inflation and excursion from the vehicle. Due to the compact design of the present invention, such protection is made available even in vehicles with limited longitudinal space for tether attachment. Furthermore, a variety of curtain compaction techniques can be used without substantially changing the configuration of the tether attachment assembly.
These and other objects, features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.